The present invention relates to a multi-stage gear shift transmission and, more particularly, to such a transmission including a plurality of forward shift stage gear trains capable of being alternatively established, and a reverse stage gear train having an idle gear portion meshed with a reverse input gear and a reverse output gear, the forward shift stage and reverse stage gear trains being provided between an input-side shaft and an output-side shaft parallel to the input-side shaft, and a reverse stage establishing clutch mechanism interposed in the middle of the reverse stage gear train.
Such transmissions are conventionally known, for example from Japanese Utility Model Application Laid-open No. 156652/87.
In the above conventional gear shift transmission, the selective establishment of the forward shift stage is conducted by the connecting operation of the forward shift stage establishing clutch mechanism, and the establishment of the reverse stage is conducted by the connecting operation of the reverse stage establishing clutch mechanism interposed between the input shaft and the reverse input gear. Moreover, the reverse stage establishing clutch mechanism generally comprises a cone portion provided in a clutch gear coupled to the reverse input gear for relative non-rotation, a ring having a tapered surface capable of frictionally engaging the cone portion, and a sleeve coupled to the input shaft and capable of being meshed with the clutch gear, so that when the reverse stage is established, the ring is urged toward the clutch gear by the sleeve to prevent the generation of gearing chatter. In such prior art, during establishment of forward stage, there is a very large relative difference in rotation speed produced between the cone portion and the tapered surface of the ring which are reversely rotating with respect to each other at a slightly spaced apart distance, and it is necessary to provide a design meeting such large difference in relative rotation speed.
The present invention has been accomplished with such circumstances in view, and it is an object of the present invention to provide a multi-stage gear shift transmission in which when the reverse stage is established, gearing chatter is prevented from being generated and no large relative difference in rotation speed is produced in the frictional engaging portions of the reverse stage establishing clutch mechanism.